The invention relates to additives useful in lubricant compositions having superior dispersant and antioxidant activity.
It is known that in the normal use of organic lubricant oils such as transmission fluids, bearing lubricants, power transmitting fluids and diesel engine lubricants, the base medium is subjected to oxidizing conditions which may result in the formation of sludge, lacquers, corrosive acids and the like. These products are undesirable since they leave oxidation residues or other solid contaminants which interfere with the normal operation of the fluid, increase its viscosity and even cause severe damage to parts of the equipment itself.
In the lubrication of modern engines, oil compositions must be able to prevent acids, sludge and other solid contaminants from maintaining contact with moving metal parts. Poor piston travel and excessive engine bearing corrosion may result unless the oil can prevent sludge and oxidation products from depositing in the engines. Superior dispersants are therefore particularly needed in new engine oils.
The most desirable way for decreasing these difficulties is to add to the base lubricant fluid an additive capable of dispersing solid particles to prevent them from interfering with the normal operation of the equipment and capable of leaving the metal surfaces relatively clean. Today with modern equipment operating under increasingly strenuous conditions, it is highly desirable to develop new detergents which have improved dispersant properties, which are soluble in the fluid lubricants to which they are added and which are themselves stable therein.
U.S. Pat. No. 4,219,431 is directed to lubricant compositions containing a lubricant and a minor amount of a derivative of alkenylsuccinic anhydride which includes the reaction product of (1) an alkenylsuccinic acid, ester or anhydride and a hydroxy aromatic compound and (2) the product of reaction between (1) and an amine, (3) the reaction product of (2) and an aldehyde and (4) the reaction product of (3) and a metal salt. To the best of applicants' knowledge and belief the reaction products disclosed herein are new and accordingly it is believed that no one has heretofore used the reaction product of an alkenylsuccinic compounds, e.g., anhydride, an arylamine and a hindered alcohol to provide products having superior dispersant/antioxidant charcteristics for lubricant compositions.